There is a great deal of interest in the concept of molecular composites due to the large increases in mechanical properties which may be realized from this type of composite material (see, e.g., U.S. Pat. No. 4,207,407 and Hwang et al., J. Macromol. Sci.--Phys., vol. B22, No. 2, pp. 231-257 (1983)). Fiber composite theory predicts that reinforcement of a matrix is controlled by the aspect ratio of the reinforcing element. Increasing the aspect ratio of the fiber is reported to increase tensile modulus by up to two orders of magnitude. Thus, the expected property improvements in molecular composites result from the reinforcement of a matrix at the molecular level by individually dispersed rigid rod polymer molecules. In addition, the formation of a molecular composite may alleviate the problem in conventional composites of failure at discrete phase separated fiber-matrix interfaces.
A recent review by Pawlikowski et al., Annu. Rev. Mater. Sci., Vol. 21, pp. 159-184 (1991), summarizes the current status of polymer molecular composites. Most of the work on molecular composites has focused on two reinforcements, poly (p-phenyleneterephthalamide) (PPTA), and the PBZ's, either poly (p-phenylenebenzobisthiazole) or poly(benzimidazole). Thermoplastic and thermoset matrices have both been explored. In general, the major obstacle to overcome in the formation of a true molecular dispersion is the immiscibility of the rigid reinforcement and flexible matrix polymers which leads to phase separation between the components. Such phase separation generally leads to the scattering of light whereby samples appear opaque and are not optically transparent.
It is an object of the present invention to provide a homogeneous molecular composite.
Another object of the present invention is to provide a homogeneous molecular composite including a liquid crystalline polymer and a liquid crystalline thermoset matrix.
Yet another object of the present invention is to provide a homogeneous molecular composite including a liquid crystalline polymer and a thermosettable liquid crystalline monomer.
Still another object of this invention is to provide a molecular composite including a liquid crystalline polymer and a liquid crystalline thermoset matrix having enhanced miscibility.
Still another object of this invention is to provide a molecular composite including a liquid crystalline polymer and a thermosettable liquid crystalline monomer having enhanced miscibility.